Many vitamins are essential for personal health, but come the wintertime, vitamin D may dominate the headlines. That’s because hours of sunlight dwindle in the winter, which can lower levels of vitamin D in the body.

Vitamin D is often called the “sunshine vitamin” because of its connection to sunlight. The Cleveland Clinic states that sun exposure on the skin is one way people can get vitamin D. However, individuals with darker skin or those living in certain geographic areas with limited sunlight may not produce enough vitamin D. In such cases, supplementation through foods or pills might be necessary.

Vitamin D helps regulate calcium levels in the body and supports the building and maintenance of strong bones. The Mayo Clinic states that low vitamin D levels have been linked to cancer, cognitive decline, multiple sclerosis, rickets, and psoriasis. But how much vitamin D does a person need? The recommended daily intake of vitamin D is 400 international units for infants up to 12 months old, 600 IU for people aged 1 to 70 years, and 800 IU for those over 70 years old. However, some doctors recommend taking higher amounts. The Endocrine Society, for example, suggests that higher daily doses of 1,500 to 2,000 IU may be necessary for adults.

Although vitamin D deficiency can harm health, it’s also unhealthy to take too much. Harvard Health warns against exceeding 4,000 IU daily, which is the safe upper limit. High doses of vitamin D can lead to excess calcium in the blood, a condition known as hypercalcemia, increasing the risk of deadly heart problems. Taking more vitamin D also raises the risk of kidney stones, so it’s crucial to weigh the benefits and risks. Symptoms of too much vitamin D include vomiting, nausea, stomach pain, fatigue, dizziness, confusion, increased thirst, and frequent urination.

Getting vitamin D naturally through sunlight and food sources is better than supplements. Fatty fish, mushrooms, liver, shrimp, and oysters are excellent sources of vitamin D. UCLA Health says that eight to 10 minutes of sun exposure at noon can produce the recommended amount of vitamin D. However, in winter, when only about 10% of the body is exposed, nearly two hours of sun exposure at noon may be needed to produce enough vitamin D. Different geographic regions may require varying amounts of exposure to ensure sufficient vitamin D production.

Vitamin D is essential for health, but many people don’t get enough. Increasing sun exposure, eating the right foods, and supplementing when necessary can boost vitamin D levels.